Robin Haase: You feel like an amateur when you play against Novak Djokovic

Former world No. 33 Robin Haase claims world No. 1 Novak Djokovic is the toughest player to play against. Haase, 33, and 32-year-old Djokovic have played three times against each other at the ATP level. Haase, a two-time ATP champion, stood no chance in each of his three clashes against the Serb.

Djokovic beat Haase in straight sets at the US Open in 2007, before he handed him a two-set loss in Basel three years later. Haase, who enjoyed his best season on the Tour in 2012, faced Djokovic at the Monte Carlo Masters that year but still even at his best couldn't beat the Serb.

"The toughest thing is to play against Novak. Without any doubt. You feel like an amateur (when you play) against him. I have never been close to a winning set against him. He doesn't have weaknesses. Against the other players there were moments when I felt I could threaten a bit -- but against him I had no idea what to do," Haase said of Djokovic, per Sport Klub.

Haase, now ranked at No. 169 in the world, believes tennis will be just fine when Djokovic, Rafael Nadal and Roger Federer retire. "I would say the answer lies in the past. People wondered the same when (Andre) Agassi and (Pete) Sampras were retiring.

The same happened when (Bjorn) Borg and (Ivan) Lendl were calling it quits," Haase said. "I don't think that tennis is in jeopardy. A player can't be bigger than the game. There is a new generation, they have beaten the best -- which is a good sign. The guys are good."